EP0356903A2 - Sytème de transmission de télévision ayant une séparation modifiée des spectres audio et vidéo - Google Patents

Sytème de transmission de télévision ayant une séparation modifiée des spectres audio et vidéo Download PDF

Info

Publication number
EP0356903A2
EP0356903A2 EP89115588A EP89115588A EP0356903A2 EP 0356903 A2 EP0356903 A2 EP 0356903A2 EP 89115588 A EP89115588 A EP 89115588A EP 89115588 A EP89115588 A EP 89115588A EP 0356903 A2 EP0356903 A2 EP 0356903A2
Authority
EP
European Patent Office
Prior art keywords
video
signal
audio
component
low pass
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP89115588A
Other languages
German (de)
English (en)
Other versions
EP0356903A3 (fr
Inventor
Yves Charles Faroudja
Jack James Campbell
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0356903A2 publication Critical patent/EP0356903A2/fr
Publication of EP0356903A3 publication Critical patent/EP0356903A3/fr
Pending legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/04—Systems for the transmission of one television signal, i.e. both picture and sound, by a single carrier

Definitions

  • THIS INVENTION relates to television transmission systems. More particularly, the invention relates to a television transmission system method and apparatus for providing improved separation of audio and video spectral components and more efficient use of the limited bandwidth television channel spectrum.
  • each recognized television transmission system has conformed to one of a predetermined few recognized television signal format standards.
  • One such standard for colour television is the NTSC standard.
  • the spectrum reserved for each single transmission channel is six Megahertz (6MHz). This relatively limited spectrum is required to contain the picture carrier including synchronizing information, the colour subcarrier and the sound carrier.
  • the separation between the picture carrier and the sound carrier is specified to be only 4.5 MHz, as graphed in Figure 1.
  • the notch filter limits video bandwidth and also introduces group delay errors resulting in ringing and chroma tansitional artifacts into the transmitted picture spectrum. In any instance, sound or picture will be degraded, and full advantage of the 6 MHz spectrum allotted to the NTSC channel, for example, will not be realised.
  • notch filter centred at 4.5 MHz is provided in the received video path in order to eliminate visual interference patterns in the picture due to the sound carrier. Again, picture quality will be significantly degraded by the receiver video path notch filter.
  • the audio signal is transmitted as frequency modulation.
  • One characteristic of such modulation is known as the "capture effect”.
  • the capture effect means that the FM discriminator at the receiver "locks onto” the FM signal, providing it manifests a predetermined minimum signal level to achieve “quieting”, and eliminates non-coherent information, such as noise and high frequency video energy groups, which is below the quieting level.
  • non-coherent information such as noise and high frequency video energy groups, which is below the quieting level.
  • a hitherto unsolved need has therefore arisen for a television transmission system which makes more effective use of the available limited channel spectrum by passing lower amplitude high frequency picture signal energy groups, while minimizing interference between the picture and sound components of the television signal, and at the same time remaining fully compatible with existing transmission and reception standards and equipment.
  • a general object of the present invention is to provide for a more effective sharing of limited channel spectrum for a television broadcast signal which provides increased video signal component bandwidth and minimized interference to and from the audio signal component while remaining compatible with existing television standards and equipment.
  • a more specific object of the present invention is to provide an adapted notch filter in the picture signal component path which operates to remove high frequency picture energy groups only as necessary in order to minimize interference between picture and sound signal components of a television transmission system.
  • Another specific object of the present invention is to measure the baseband picture signal content in order to develop a control signal for adaptively controlling the operational characteristics of a picture carrier notch filter centred about the aural carrier nominal centre frequency.
  • Another specific object of the present invention is to relate the phase of the aural subcarrier to the phase of the picture signal horizontal synchronizing information in order to enable separation of low frequency aural information and picture information via comb filter techniques.
  • One more specific object of the present invention is to provide adaptive enhancement processes to television picture signals at both the transmit and receive ends of the transmission system in order to improve overall picture bandwidth and apparent sharpness without interference to or from the aural signal component.
  • the invention provides a method of providing improved separation of audio and video spectra carried upon spectrally separated audio and video carriers within a television transmission channel leading to a television receiver, which method comprising the transmission steps of: obtaining a high frequency luminance component at the vicinity of the audio carrier offset from the video carrier from a full bandwidth baseband luminance signal received from a video source; limiting the amplitude of luminance energy groups within the high frequency component to be below a predetermined amplitude level; combining the amplitude limited high frequency component into the full bandwidth luminance signal in a manner which provides a composite luminance signal having amplitude limited high frequency energy groups at the vicinity of the audio carrier; adding video synchronizing information to the composite luminance signal to provide a single video modulation signal; modulating said video carrier with said single video modulation signal; combining the video carrier with the audio carrier into a resultant television composite; and passing the resultant television composite through the television transmission channel to the television receiver.
  • the method of the present invention may include the reception steps of: passing a received and separated video signal through two paths constituting a main path and an enhancement path; generating a transition shortened, enhancement video signal from said separated video signal; deriving a multiplier control signal in a range from zero to unity from transition amplitudes present in the separated video signal; multiplying said enhancement video signal by said multiplier control signal to generate a threshold selected enhancement video signal; and adding the main path separated video signal and the threshold selected enhancement video signal together in proper phase relation­ship to provide an adaptively enhanced separated video signal at said receiver.
  • the method also may include the further steps of: receiving baseband audio from a source; sampling said baseband audio at a rate related to said video synchronizing information to provide an audio sample signal; controlling with said audio sample signal the frequency stepping operation of a frequency stepping oscillator to generate frequency steps wherein each step is an odd multiple of one half of the video synchronizing information rate; and generating said audio carrier in accordance with said frequency steps so as to be phase coherent with said video synchronizing information.
  • the method may further comprise at the reception end the steps of: passing a received and separated video signal having audio energy groups to be separated through two paths constituting a main path and a bandpass filtered path having a passband centred about the nominal centre frequency of the baseband audio carrier; obtaining a received video band rejected path from said main path and said bandpass filtered path; comb filter separating said audio energy groups out of the received video signal passing through said bandpass filtered path to provide a comb filtered video signal component; and combining said received video band rejected path and said comb filtered video signal component in proper phase relationship to provide a full band received video signal in which audio energy groups have been removed by comb filter separation.
  • a baseband colour video filtering processor 10 is illustrated in Figure 3.
  • the filtering unit is preferably combined within an encoder of the type generally depicted in Figure 4 of U.S. Patent No. 4,731,660, incorporated herein by reference.
  • the processor 10 includes a synchronizing information input 12, a chroma input 14, a luminance input 16 and an output 18.
  • the synchronizing information at the input 12 is passed through a low pass filter 20 and sent via a line 21 to provide one input to an adder circuit 22.
  • the low pass filter 20 has the F1 characteristic which is depicted in Figure 4A. This filter 20 has a minus 6DB point at 3 MHz and cuts off at a zero located at 4.5 MHz.
  • the filter 20 has the function of softening the otherwise sharp transition edges of sync pulses so as to eliminate high frequency energy groups thereof lying within the aural carrier spectrum. It has been found in practice that sharp edges are not required on synchronizing pulses in order for these pulses to accomplish their intended function at the receiver end.
  • Combed chroma information at the input 14 is passed through a low pass filter 24 and sent via a line 25 to a second input of the adder circuit 22.
  • the low pass filter 24 has the characteristic depicted in Figure 4B as being flat until about 4MHz and then having a very steep attenuation characteristic to a zero (20DB down) located at 4.5 MHz.
  • This filter 24 may be implemented by a Matthey Type MCL420B filter which is presently commercially available.
  • the first luminance path passes through the low pass filter structure 28 having the characteristic depicted in Figure 4A and leads via a line 29 to an adder circuit 34.
  • the second luminance path passes through the high pass filter structure 30 having the characteristics depicted in Figure 4C and leads via a line 31 to a soft switch-limiter 36.
  • the characteristics of the high pass filter structure 30 are complementary to the characteristics of the low pass filter structure 20, i.e. if one were to apply the same signal to both filters 20 and 30 and then to sum the outputs thereof, the signal would not manifest any attentuation with frequency.
  • the third luminance path is converted into a control signal by operation of the control signal generator 32 (described hereinafter in greater detail in conjunction with Figures 10A and 10B).
  • the resultant control signal is put out via a line 33 to control the operation of the soft switch-limiter 36.
  • the switch-limiter 36 operates upon the high frequency luminance energy groups so that they are amplitude-limited to a maximum predetermined amplitude below a level determined to cause interference in the audio signal recovery process at the receiver.
  • the amplitude-limited energy groups passed by the switch-limiter 36 are sent via a line 37 to the adder 34 wherein they are combined in proper phase relation with the low pass filtered luminance energy groups passed by the filter 28.
  • the resultant luminance signal is put out on a line 35 which leads to a third input of the adder circuit 22.
  • the adder 22 combines in proper phase relation the low pass filtered synchronizing information on the line 21, the filtered chrominance on the line 25 and the adaptively filtered luminance on the line 35 into a composite video signal which is put out on the output line 18 to the RF modulator of the picture signal transmitter (not shown) of the transmission system.
  • Figure 5 depicts a structure 38 for implementing the low pass filters 20, 28 of the processor 10 depicted in Figure 3 and having the Figure 4A characteristic in an NTSC signal format.
  • the filter 38 includes an input 40 and an output 42. Video received at the input is put through a string of predetermined delays, a first 50 nanosecond delay 44, a first 110 nanosecond delay 46, a second 110 nanosecond delay 48 and a second 50 nanosecond delay 50. Taps 45, 47 and 49 respectively separate the elements 44, 46, 48 and 50; and an output tap 51 leads from the last delay element 50.
  • Total delay through the delay line comprising the elements 44, 46, 48 and 50 is 320 nanoseconds, and the 160 nanosecond half length structure of the total delay is configured to provide a zero at approximately 4.5 MHz.
  • the object of design of the filter 38 is to prevent addition of unwanted artifacts such as group delay errors or ringing to video signals flowing through its passband.
  • Video at the filter input is passed through an amplifier 52 having a minus one-half amplitude gain characteristic, and the resultant signal is put out on a line 53.
  • Video from the tap 45 is passed through a plus one-half amplitude gain amplifier 54, and the resultant signal is put out on a line 55.
  • Video from the tap 47 is connected as one full unit gain input to an adder circuit 56 and as one full unit gain input to another adder circuit 62.
  • Video from the tap 49 is passed through a plus one-­half amplitude gain amplifier 58, and the resultant signal is put out on a line 59.
  • Video from the last tap 51 is passed through a minus one-half amplitude gain amplifier 60 and put out on the line 61.
  • the signals on the lines 55 and 59 are added in the adder circuit 56 along with the signal on the line 47.
  • the resultant sum is put out on a line 57 to a third adder circuit 66; and the signal on the line has the characteristic of Waveform A in Figure 6.
  • the signals on the lines 53 and 61 are added in the adder circuit 62 along with the signal on the line 47.
  • the output from the adder circuit 62 passes through an adjustable balance resistor 64, whose wiper 65 leads to the adder circuit 66.
  • the signal on the wiper or tap 65 has the characteristic of Waveform B in Figure 6.
  • the output of the adder circuit 66 is provided on a line 67 leading to a 4.5 MHz Bessel filter 68, the output of which provides the filter output 42.
  • the output on the line 67 has the characteristic of Waveform C in Figure 6; and, the output on the line 42 has the characteristic of Waveform D thereof, which is approximately minus 6 DB at 3 MHz and minus 20 DB at 4.5 MHz
  • FIG. 7 An alternative adapted low pass filter 26′ is depicted in Figure 7 as having a luminance input 70 and an adaptively filtered luminance output 72.
  • the luminance input 70 is split into two paths: a first path leading through a low pass filter 74 having the characteristic depicted in Figure 4A and implemented, for example, as the structure 38 depicted in Figures 5 and 6 and discussed above in connection therewith; and a second or main path leading through a delay line 76 having a delay selected to match the delay through the circuit 74 (e.g. nominally 160 nanoseconds).
  • the low-pass-filtered component put out by the filter 74 is subtracted from the phase matched, delayed unfiltered baseband luminance component put out by the delay match 76 in a subtractor circuit 78 in order to achieve a high pass filter structure of the type whose output characteristic is depicted as Figure 4C and which is the pass band complement of the filter characteristic depicted as Figure 4A.
  • the elements 76 and 78 may be combined with the element 28 in accordance with Figure 7 in order to achieve the high pass filter 30 depicted in Figure 3).
  • An output 79 from the subtractor 78 is passed through a threshold circuit 80 which passes luminance high frequency energy groups above a predetermined threshold, e.g. 4o to 60 IRE units. These energy groups are then subtracted from the luminance full baseband signal put out from the delay match 76 by operation of a second subtractor circuit 82.
  • the output 72 of the second subtractor 82 is thus a luminance signal in which high amplitude, high frequency luminance energy groups have been eliminated in order to prevent interference with the sound channel spectrum.
  • This implementation 26′ of the adaptive low pass filter structure eliminates the need for a control circuit and accomplishes adaptive low pass filtering of luminance by operation of the threshold circuit 80.
  • the high frequency luminance energy groups are below the threshold, they pass through the subtractor 82 unaffected.
  • they are above the threshold, they are subtracted proportionally, so that the energy groups put out by the subtractor 82 are of amplitudes below the threshold level, irrespective of incoming amplitude.
  • FIG 8 Yet another preferred implementation 26 ⁇ of the adaptive low pass filter 26 depicted in Figure 3 is found in Figure 8.
  • a luminance input 84 leads to an adaptively filtered luminance output 86 via the Figure 4C high pass filter structure realised with the elements 74, 76 and 78 as discussed in conjunction with Figure 7; and via a multiplier 90 and adder 92.
  • a control circuit 94 generates a multiplier control signal, having a characteristic as graphed in Figure 8A.
  • the gain characteristic of the multiplier 90 is seen to be a function of IRE transition level and the control slope and consequent gain characteristic is easily controlled by the designer.
  • a television receiver enhancement processor 100 is depicted in Figure 9. It has a luminance input 102 which comes from luminance/chrominance separation circuitry within the receiver; and it has an output 104 leading to the luminance video amplifier stage of the receiver.
  • One path of incoming luminance leads through an enhancement process, such as the video crispening process described in U.S. Patent No. 4,030,121, the disclosure of which is incorporated herein by reference.
  • the processes described therein shorten luminance (and chroma) transition times and thereby add sharpness or crispness to the resultant picture image.
  • the crispened video path exits the enhancement process 106 on a line 107 which leads to a multiplier 108 and thence, on a line 109, to one input of an adder circuit 110.
  • Another path for the incoming luminance on the line 102 leads through a delay matching circuit 112 which matches the delays inherent in the processes 106 and 108 to another input of the adder circuit 110.
  • the delay matched main path video (which has had high amplitude, high frequency luminance energy groups attenuated adaptively at the transmitter end of the system) is combined with an adaptively determined enhancement component put out by the multiplier 108.
  • a third path for the incoming luminance is to a control signal generator 114.
  • the control signal generator 114 generates a multiplier control signal as graphed in Figure 9A which controls the gain characteristic (between zero and unity) of the multiplier 108.
  • the graph of 9A is generally the complement of the control signal graphed in Figure 8A.
  • FIG. 10A and 10B Two control circuits for generating multiplier control signals are depicted in Figures 10A and 10B.
  • a first such circuit 114 is depicted in Figure 10A and includes a luminance input 116 and a multiplier control ouput line 118.
  • the input 116 leads through a very narrow pass band FM audio bandpass filter 120 having a bandpass characteristic as graphed in Figure 4D.
  • the resultant signal comprising high frequency luminance energy groups lying within the FM audio passband, is full wave rectified in a full wave rectifier circuit 122 in order to remove the sense of each transition and to provide an absolute value.
  • the absolute value signal is shaped in a wave shape circuit 124 to have the desired multiplier control signal waveshape, e.g. Figure 8A, and put out on the line 118 to control the multiplier gain characteristic between zero and unity.
  • FIG. 10B Another control circuit 126 having a broader passband and providing a more robust multiplier gain control signal is depicted in Figure 10B.
  • the Figure 4C high pass filter structure comprising the elements 74, 76 and 78, discussed previously, is connected to an input 128.
  • the output from the high pass filter structure leads through the rectifier 122 and shaper 124 to a multiplier gain characteristic control line 130.
  • One advantage of the control circuit 126 over the circuit 114 is that cross colour artifacts are also removed.
  • Figure 11 depicts an audio frequency shift modulator circuit 140 which is phase locked to the horizontal scan frequency and is such that the FM modulation always follows the function: where F H equals the horizontal line scan frequency and where N equals a number which varies in accordance with the FM modulation.
  • the depicted modulator is actually a frequency shift modulator rather than a true analog frequency modulation modulator.
  • the FM carrier shifts between values which are odd multiples of one half of the horizontal line scan rate.
  • the circuit 140 includes a horizontal sync input 142, an audio input 144 and an FM modulation component output 146. Since the horizontal line scan rate in the NTSC system is nominally 15,734 Hertz, the Nyquist sampling limitation is one half the scan rate, or 7,867 Hz. Otherwise, undesirable audio aliases will be produced. Thus, two complementary filters 148 and 150 having crossover points at approximately 7500 Hz effectively separate the audio spectrum into two segments, a low frequency segment passed by the filter 148, and a high frequency segment passed by the filter 150.
  • the low frequency audio segment having a characteristic graphed as Waveform A in Figure 12, is applied as an input to a sampler circuit 152 wherein amplitudes samples are taken at the line scan rate, graphed as Waveform B in Figure 12.
  • the resultant samples, graphed as Waveform C in Figure 12 are applied to control a frequency stepping oscillator 154 which steps between frequencies which are odd multiples of one half of the line scan rate at a rate directly proportional to the sample amplitudes as graphed at Waveform C, Figure 12.
  • the resultant modulation, Waveform D of Figure 12 is applied to a 90 degree phase shift circuit 156 and to an adder circuit 158.
  • the audio high frequency segment put out by the filter 150 is applied as one input to an AM suppressed carrier modulator 160, the other input being provided by the output from the 90 degree phase shift modulator.
  • the resultant quadrature modulation of the audio high frequencies, Waveform E of Figure 12 is then added with the baseband modulation, Waveform D of Figure 12, in the adder circuit 158, in order to produce a resultant modulation vector graphed as Waveform F of Figure 12.
  • Figure 13 illustrates somewhat diagrammatically the relationship between the audio FM carrier and the horizontal sync frequency.
  • a simple comb filter structure 162 in the luminance path at the television receiver eliminates the phase locked audio signal from the luminance.
  • the structure included an input 164 for receiving video and audio, and an output 166 for putting off full bandwidth luminance in which the audio has been removed by comb filter separation techniques.
  • AM modulation of a carrier in phase quadrature with the carrier itself is equivalent to phase or frequency modulation
  • a conventional audio FM demodulator circuit within an ordinary television receiver will recover the quadrature modulated audio high frequencies by usual means. It is also possible to use an extra subcarrier to carry vastly improved audio high frequencies and demodulate them in a non-standard way in a specially adapted receiver.
  • Incoming video (including the interleaved audio FM energy groups) is separated into two paths, a first path through a4.5 MHz bandpass filter 168 having the characteristic graphed in Figure 14A; and, a second path through a delay match circuit 170 having a delay to match the delay of the filter 168.
  • An output line 169 from the filter 168 is subtracted from the delay matched video signal put out from the delay match 170 on a line 171 by operation of a subtractor circuit 172.
  • the resultant signal on a line 173 includes all of the baseband video spectrum, except the portion thereof notched out by the bandpass filter 168, as graphed in Figure 14B.
  • the notch filtered video at the baseband audio carrier frequency (4.5 MHz) on the line 169 enters a simple 1 H comb filter structure comprising a 1 H delay line 176 having an output line 177 and an adder circuit 178.
  • Undelayed notch filtered video on the line 169 and 1 H delayed notch filtered video on the line 177 are added together in the adder circuit 178 so that the interleaved audio frequency energy groups (modulated at odd multiples of one half the line scan rate) are phase cancelled from line to line.
  • the resultant signal being video from which audio has been cancelled by comb filtering, is passed through a one half unity gain amplifier 180 and then combined with the band rejected video signal in an adder circuit 174.
  • the signal put out by the adder circuit 174 is full bandwidth video in which the audio component has been removed by comb filter separation, as shown in Figure 14C.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Television Systems (AREA)
  • Filters That Use Time-Delay Elements (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
  • Television Receiver Circuits (AREA)
EP19890115588 1988-09-01 1989-08-23 Sytème de transmission de télévision ayant une séparation modifiée des spectres audio et vidéo Pending EP0356903A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US07/239,298 US4943849A (en) 1988-09-01 1988-09-01 Television transmission system having improved separation of audio and video spectra
US239298 1988-09-01

Publications (2)

Publication Number Publication Date
EP0356903A2 true EP0356903A2 (fr) 1990-03-07
EP0356903A3 EP0356903A3 (fr) 1991-10-09

Family

ID=22901546

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890115588 Pending EP0356903A3 (fr) 1988-09-01 1989-08-23 Sytème de transmission de télévision ayant une séparation modifiée des spectres audio et vidéo

Country Status (3)

Country Link
US (1) US4943849A (fr)
EP (1) EP0356903A3 (fr)
JP (1) JPH02210992A (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992022984A1 (fr) * 1991-06-14 1992-12-23 Wavephore, Inc. Transmission de donnees par signal video
US5387941A (en) * 1991-06-14 1995-02-07 Wavephore, Inc. Data with video transmitter
US5410360A (en) * 1991-06-14 1995-04-25 Wavephore, Inc. Timing control for injecting a burst and data into a video signal
US5555024A (en) * 1994-12-23 1996-09-10 Samsung Electronics Co., Ltd. Transmitters for burying digital signals within the trace and retrace intervals of NTSC television signals
US5559559A (en) * 1991-06-14 1996-09-24 Wavephore, Inc. Transmitting a secondary signal with dynamic injection level control
US5617148A (en) * 1991-06-14 1997-04-01 Wavephore, Inc. Filter by-pass for transmitting an additional signal with a video signal
US5831679A (en) * 1991-06-14 1998-11-03 Wavephore, Inc. Network for retrieval and video transmission of information

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09322195A (ja) * 1996-05-31 1997-12-12 Sony Corp 信号トラップ装置および方法、記録媒体再生装置および方法、並びに信号抽出装置および方法
US5923374A (en) * 1996-08-08 1999-07-13 Lucent Technologies Inc. Method and apparatus for reduced-bandwidth transmission of television signals
AU2002332706A1 (en) * 2001-08-30 2003-03-18 Faroudja Cognition Systems, Inc. Multi-layer video compression system with synthetic high frequencies
US7280159B2 (en) * 2004-06-16 2007-10-09 Realtek Semiconductor Corp. Method and apparatus for cross color and/or cross luminance suppression
US7460180B2 (en) * 2004-06-16 2008-12-02 Realtek Semiconductor Corp. Method for false color suppression
US7271850B2 (en) * 2004-06-16 2007-09-18 Realtek Semiconductor Corp. Method and apparatus for cross color/cross luminance suppression
CN108784694A (zh) * 2018-04-23 2018-11-13 京东方科技集团股份有限公司 一种信号采集电路、信号采集方法及可穿戴设备
CN116248925A (zh) * 2023-01-03 2023-06-09 珠海亿智电子科技有限公司 一种模拟高清视频数据传输方法及相关设备

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2033220A1 (de) * 1970-07-04 1972-01-27 Fernseh Gmbh Modulationsverfahren fur elektrische Signale, insbesonders Fernsehsignale
US4030121A (en) * 1975-12-02 1977-06-14 Faroudja Y C Video crispener
US4179705A (en) * 1978-03-13 1979-12-18 Faroudja Y C Method and apparatus for separation of chrominance and luminance with adaptive comb filtering in a quadrature modulated color television system
US4262304A (en) * 1979-07-16 1981-04-14 Faroudja Y C Low level/signal booster for television transition
GB2133252A (en) * 1982-12-17 1984-07-18 Philips Electronic Associated Television transmitter
DE3633882A1 (de) * 1986-10-04 1988-04-14 Inst Rundfunktechnik Gmbh Digitales hoerfunkuebertragungssystem
US4731660A (en) * 1987-02-20 1988-03-15 Yves C. Faroudja Processing methods using adaptive threshold for removal of chroma/luminance cross-talk in quadrature-modulated subcarrier color television systems

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992022984A1 (fr) * 1991-06-14 1992-12-23 Wavephore, Inc. Transmission de donnees par signal video
US5327237A (en) * 1991-06-14 1994-07-05 Wavephore, Inc. Transmitting data with video
US5387941A (en) * 1991-06-14 1995-02-07 Wavephore, Inc. Data with video transmitter
US5410360A (en) * 1991-06-14 1995-04-25 Wavephore, Inc. Timing control for injecting a burst and data into a video signal
US5557333A (en) * 1991-06-14 1996-09-17 Wavephore, Inc. System for transparent transmission and reception of a secondary data signal with a video signal in the video band
US5559559A (en) * 1991-06-14 1996-09-24 Wavephore, Inc. Transmitting a secondary signal with dynamic injection level control
US5572247A (en) * 1991-06-14 1996-11-05 Wavephore, Inc. Processor for receiving data from a video signal
US5587743A (en) * 1991-06-14 1996-12-24 Wavephore, Inc. Signal processors for transparent and simultaneous transmission and reception of a data signal in a video signal
US5617148A (en) * 1991-06-14 1997-04-01 Wavephore, Inc. Filter by-pass for transmitting an additional signal with a video signal
US5666168A (en) * 1991-06-14 1997-09-09 Wavephore, Inc. System for transmitting facsimile data in the upper vestigial chrominance sideband of a video signal
US5831679A (en) * 1991-06-14 1998-11-03 Wavephore, Inc. Network for retrieval and video transmission of information
US5555024A (en) * 1994-12-23 1996-09-10 Samsung Electronics Co., Ltd. Transmitters for burying digital signals within the trace and retrace intervals of NTSC television signals

Also Published As

Publication number Publication date
US4943849A (en) 1990-07-24
EP0356903A3 (fr) 1991-10-09
JPH02210992A (ja) 1990-08-22

Similar Documents

Publication Publication Date Title
JP4131483B2 (ja) 単一送信装置による音声のアナログ・デジタル混合放送方法およびそのための装置
US4943849A (en) Television transmission system having improved separation of audio and video spectra
KR960020472A (ko) 디지탈 비디오 신호 처리 시스템
CN1075583A (zh) 数字电视信号接收机的自动增益控制装置
WO1998035492A2 (fr) Reconnaissance de sequences video
EP0556306A1 (fr) Systeme de transmission blr pour television a haute definition a interference reduite dans un meme canal ntsc.
CA2086239A1 (fr) Methode et appareil d'annulation de distorsions en quadrature dans les signaux video a composantes en quadrature
US4403255A (en) FM/TV Automatic gain control system
CA1227566A (fr) Filtre a frequence intermediaire a correction de la modulation de phase de nyquist
US4956862A (en) Method of providing sound privacy system compatible with mono and btsc stereo audio
US3504115A (en) Fm television signal transmission system
US4602288A (en) Intermediate frequency saw filter with nyquist phase modulation correction
KR100263573B1 (ko) 스테레오 라디오 수신기에서의 멀티 플렉스 신호의 복호화 회로
US5561473A (en) Contour correction signal generating circuit
US3961135A (en) Synchronized demodulation system
KR950012662B1 (ko) 티브이 고스트의 모델링 시스템
KR100941823B1 (ko) Ｄｒｍ/ａｍ 동시 송출
CA1308445C (fr) Elimination des parasites dans les signaux transmis et demodulation de signaux a bande laterale residuelle
JP2575385B2 (ja) 多重伝送方法およびそのための送受信装置
KR940006741B1 (ko) 전송장치
EP0563167B1 (fr) Preaccentuation non lineaire compatible pour signaux video composites
JP2678692B2 (ja) ディジタル多重化伝送方法および送受信装置
RU2054824C1 (ru) Цифровое устройство разделения сигналов яркости и цветности в декодерах систем pal и ntsc
RU2054820C1 (ru) Цифровое устройство разделения сигналов яркости и цветности в декодерах систем pal и ntsc
JPH09163330A (ja) 静止画像・音声多重装置、静止画像・音声多重装置用送信装置及び静止画像・音声多重装置用受信装置

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE GB IT

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

18W Application withdrawn

Withdrawal date: 19910710

D18W Application withdrawn (deleted)
AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE GB IT

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19911009

D18W Application withdrawn (deleted)